IFNG and COVID-19: Of note, in our study, we show that IFNγ production was significantly reduced in MP-stimulated PBMC from patients with severe COVID-19 compared with those with OTD and this, together with increased expression of Tim-3 and/or PD-1 on PBMC, plausibly suggests that patients with severe COVID-19 have an increased frequency of circulating exhausted T cells compared with patients with OTD.